CN102033088A - Preparation method of gold nano-particle/carbon nano tube composite material and application thereof - Google Patents
Preparation method of gold nano-particle/carbon nano tube composite material and application thereof Download PDFInfo
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Abstract
本发明公开了一种金纳米粒子/碳纳米管复合材料的制备方法及其用途。所述金纳米粒子/碳纳米管复合材料的制备方法包括步骤：(1)将碳纳米管和HAuCl4溶液混合，微波加热1-3分钟，得到热溶液1；(2)将热溶液1和柠檬酸钠溶液混合，微波辐射4-6分钟，得到热溶液2；和(3)将热溶液2冷却至室温，得到悬浮液，离心、过滤，得到金纳米粒子/碳纳米管复合材料。本发明提供的金纳米粒子/碳纳米管复合材料可用于检测待测样品中重金属Hg的含量。The invention discloses a preparation method and application of a gold nanoparticle/carbon nanotube composite material. The preparation method of the gold nanoparticle/carbon nanotube composite material comprises the steps: (1) mixing the carbon nanotube and the HAuCl solution, and heating by microwave for 1-3 minutes to obtain the hot solution 1; (2) mixing the hot solution 1 and the The sodium citrate solution is mixed, microwaved for 4-6 minutes to obtain hot solution 2; and (3) the hot solution 2 is cooled to room temperature to obtain a suspension, centrifuged and filtered to obtain a gold nanoparticle/carbon nanotube composite material. The gold nanoparticle/carbon nanotube composite material provided by the invention can be used to detect the content of heavy metal Hg in a sample to be tested.
Description
Technical field
The present invention relates to nano material and analytical chemistry field, relate in particular to a kind of preparation method and its usage of golden nanometer particle/carbon nano tube compound material.
Background technology
Metal nanoparticle has been successfully applied to the research of a lot of aspects owing to its significant physics and chemical property.In recent years, metal nanoparticle loads on some other carrier, for example: carbon nano-tube, conducting polymer, semiconductor or the like become the focus of research.These composite nano materials are because have the array of particles that bigger specific surface area and high order are arranged, thereby being difficult for reaching capacity during reaction obtains higher utilization ratio.Metal nanoparticle/carrier composite material, not only useful area is big, has more superior performance simultaneously when specific application.
As everyone knows, mercury is a kind of the mankind to be had the material of very big harm, and it is very easily polluted food and water body by all means by the pollutant in the environment, the health of harmful to human.The method of analyzing and testing Hg (II) has much at present, and major part is a spectrum detection method, for example, and atomic absorption spectrography (AAS), inductively coupled plasma emission spectrography, atomic fluorescence method etc.But these method complicated operations, technical requirement height, and instrument and equipment complexity cost an arm and a leg, and application is very limited.
Electrochemical methods be a kind of sensitivity, reliably, analytical approach efficiently, be widely used in the analysis and the detection of multiple metallic element and toxic pollutant.Multiple electrode material, for example gold, platinum and some chemically modified electrodes etc. all have been applied to the detection and the analysis of mercury.The gold disc electrode is considered to a kind of good working electrode because mercury is had high sensitivity.But golden disc electrode is measured mercury and is also had many weak points, the preenrichment of mercury causes mercury easily to be diffused into the surface of golden disc electrode, during stripping repeatedly the cleaning electrode stability and the reappearance that also are difficult to remove fully when just causing golden disc electrode to measure mercury like this reduce greatly.So the reparation of golden disc electrode and the difficult problem that regeneration becomes research, at present a lot of researchs are striving to find way and the approach that solves this difficult problem.
Therefore, this area presses for provides a kind of new type of metal nano particle/carrier composite material, also need simultaneously to provide a kind of new, effectively detect the method for Trace Hg.
Summary of the invention
The present invention aims to provide the preparation method of a kind of golden nanometer particle/carbon nano tube compound material (Au-NPs/CNTs compound substance), makes the golden nanometer particle/carbon nano tube compound material that obtains have good performance.
Another object of the present invention provides the purposes of golden nanometer particle/carbon nano tube compound material provided by the invention.
A further object of the present invention provides a kind of by the golden nanometer particle provided by the invention/modified electrode of carbon nano tube compound material coating and the preparation method of described modified electrode.
The 4th purpose of the present invention provides the qualitative and/or method for quantitatively determining of trace Hg (II) in a kind of testing sample.
In a first aspect of the present invention, the preparation method of a kind of golden nanometer particle/carbon nano tube compound material (Au-NPs/CNTs compound substance) is provided, described method comprises step:
(1) with carbon nano-tube and HAuCl
4Solution mixes, and microwave heating 1-3 minute, obtains hot solution 1;
(2) hot solution 1 and sodium citrate solution are mixed, microwave radiation 4-6 minute, obtain hot solution 2; With
(3) hot solution 2 is cooled to room temperature, obtains suspending liquid, centrifugal, filtration obtains golden nanometer particle/carbon nano tube compound material.
In another preference, with HAuCl
4The cumulative volume meter of solution, HAuCl
4Concentration be 0.5-2w/v%.
In another preference, step joins HAuCl with carbon nano-tube in (1)
4In the solution, ultrasonic dispersion 5-30 minute obtains scattered solution, and described scattered solution dilutes with redistilled water, obtains dilute solution, and described dilute solution microwave heating 1-3 minute obtains hot solution 1.
At another preference, in the step (1), microwave power is 400-800 watt.
In another preference, in the step (2), the blending ratio of carbon nano-tube and sodium citrate is 0.5-2mg: 4ml; In the cumulative volume of sodium citrate solution, the concentration of sodium citrate is 0.5-2w/v%.
In a second aspect of the present invention, the golden nanometer particle/carbon nano tube compound material that provides a kind of aforesaid preparation method to obtain.
In a third aspect of the present invention, a kind of the above purposes of golden nanometer particle/carbon nano tube compound material provided by the invention is provided, be used for detecting the content of testing sample heavy metal Hg.
In another preference, golden nanometer particle/carbon nano tube compound material provided by the invention is used for the qualitative and/or quantitative measurement of testing sample trace Hg.
In another preference, described testing sample is selected from surface water.
In a fourth aspect of the present invention, a kind of modified electrode is provided, described modified electrode comprises:
One base electrode, i.e. glass-carbon electrode;
One is coated on the golden nanometer particle/carbon nano tube compound material aforesaid provided by the invention on base electrode surface.
In another preference, the amount that is coated on the described golden nanometer particle/carbon nano tube compound material on base electrode surface is 5-15 μ l.
In a fifth aspect of the present invention, a kind of preparation method of aforesaid modified electrode is provided, described method comprises step:
(a) aforesaid golden nanometer particle/carbon nano tube compound material provided by the invention and dimethyl sulfoxide (DMF) are mixed, obtain decorating liquid; With
(b) will modify drop and be applied to the glass-carbon electrode surface, obtain aforesaid modified electrode provided by the invention.
In another preference, in the step (a), the amount ratio of golden nanometer particle/carbon nano tube compound material and dimethyl sulfoxide is 0.5-2mg: 2ml.
In another preference, step (a) is that golden nanometer particle/carbon nano tube compound material provided by the invention is scattered in dimethyl sulfoxide (DMF) solution, and is ultrasonic even, obtains decorating liquid.
In another preference, through handling, described processing comprises glass-carbon electrode after polishing on the W7 abrasive paper for metallograph, uses Al the glass-carbon electrode in the step (b)
2O
3Suspension sanding and polishing on chamois leather becomes minute surface, and successively at HNO
3With in the water ultrasonic several minutes, natural airing was stand-by.
In a sixth aspect of the present invention, the qualitative and/or method for quantitatively determining of trace Hg (II) in a kind of testing sample is provided, described method comprises step:
(i) testing sample is joined in the electrolytic cell, with aforesaid modified electrode provided by the invention is working electrode, Ag/AgCl is a contrast electrode, the Pt silk is that auxiliary electrode constitutes three-electrode system, regulate sedimentation potential E=-0.2-0V, sedimentation time 60-300 second, thus trace Hg (II) is enriched on the aforesaid modified electrode provided by the invention;
(ii) regulate the stripping current potential between 0-0.8V, thereby make the heavy metal ion stripping; With
(iii) analyze trace Hg (II) ion stripping spike potential and electric current, obtain the qualitative and/or quantitative result of Hg in the testing sample (II).
In another preference, in step (i), adopt potentiostatic method enriched in metals ion.
In another preference, after step (a) finishes, static 5-40 second (preferably 10-15 second).
In another preference, also comprise in (iii) in step, the stripping spike potential and the electric current of standard model under each metallic ion stripping spike potential and peak current and the same detection condition compared or calculate, thereby learn the content of Hg in the test sample (II).
In another preference, the electrolyte in the electrolytic cell is selected from the H of 0.05-0.2mol/L
2SO
4, H
3PO
4, HCl, HClO
4, or HNO
3Solution; More preferably be HClO
4Solution.
In another preference, described electrolytical concentration is 0.08-0.12mol/L.
In another preference, described deposition voltage is at-0.1-0V.
In another preference, the time of described enrichment is 1-10 minute; It more preferably is 2-7 minute.
In view of the above, the invention provides a kind of new type of metal nano particle/carrier composite material, also provide simultaneously a kind of new, effectively detect the method for Trace Hg.
Description of drawings
Fig. 1 has shown the pattern and the performance characteristic of Au-NPs/CNTs compound substance provided by the invention; Wherein
A is transmission electron microscope figure; B is energy dispersive X-ray spectrum figure.
Fig. 2 has shown the UV-Vis spectrogram of nanometer gold size (a) and Au-NPs/CNTs compound substance provided by the invention suspending liquid (b) after centrifugal.
Fig. 3 has shown that Au-NPs/CNTs nano composite material modified glassy carbon electrode provided by the invention is at 0.1mol/L H
2SO
4Cyclic voltammogram in the solution; Wherein
(a) be the 0.5mg/mL Au-NPs/CNTs nano composite material provided by the invention modified glassy carbon electrode of 5 μ l; (b) be 10 μ l; (c) be 15 μ l; Dotted line is the cyclic voltammogram (voltage range :-0.1-+1.4V (vs.Ag/AgCl of pure CNTs modified glassy carbon electrode; Sweep speed: 100mV/s).
Fig. 4 has shown the influence to Hg (II) peak current of electrolyte solution (A) and deposition voltage (B).
Fig. 5 has shown the chemical property comparison diagram of detection trace Hg (II); Wherein
(a) be naked CNTs electrode; (b) be the solid gold electrode; (c) be Au-NPs/CNTs composite electrode provided by the invention.
Fig. 6 has shown that solid gold disc electrode detects the stripping voltammogram of variable concentrations Hg (II); Wherein
A is the stripping voltammogram that solid gold disc electrode detects low concentration Hg (II), (a) blank wherein, (b) 3nM, (c) 5nM, (d) 10nM, (e) 15nM, (f) 20nM and (g) 25nM;
B is the stripping voltammogram that golden disc electrode detects high concentration Hg (II), (a) blank wherein, and 30,50,70,90,110,150,200,250,300,350,400,500,550,600nM of Hg (II) (curve b → q).
Fig. 7 has shown that Au-NPs/CNTs nano composite material modified glassy carbon provided by the invention detects the stripping voltammogram of variable concentrations Hg (II); Wherein
A detects (a) blank (dotted line), and (b) 0.5, (c) 1.0, (d) 1.5, (e) 2, (f) 3, (g) 4 and (h) the stripping voltammogram of 5nM Hg (II);
B detects (a) blank solution and (b) adds 5 * 10 continuously
-8The stripping voltammogram of mol/L Hg (II).
Fig. 8 has shown that Au-NPs/CNTs compound substance provided by the invention detects the stripping voltammogram of face of land underwater trace Hg (II); Wherein
(a) be sample solution; (b → e) adds 1 * 10 continuously
-8The standard solution of mol/L Hg (II).
Embodiment
The inventor is through extensive and deep research, be surprised to find that and utilize the microwave radiation Au-NPs/CNTs compound substance of synthetic excellent performance fast, further, the inventor finds to use Au-NPs/CNTs compound substance provided by the invention can improve the chemical property that detects Trace Hg significantly as the detection that working electrode is applied to trace Hg (II), have that the range of linearity is wide, highly sensitive, favorable reproducibility, advantage such as reusable, and be successfully applied to the detection of trace Hg (II) in the testing sample.On this basis, finished the present invention.
As used herein, Au-NPs is a golden nanometer particle, and CNTs is a carbon nano-tube.
As used herein, " Au-NPs/CNTs compound substance " is identical with the implication of " Au-NPs/CNTs nano composite material ", can exchange use.
Au-NPs/CNTs compound substance provided by the invention is that the CNTs through pre-treatment is joined HAuCl
4Solution is (preferably, with HAuCl
4The cumulative volume meter of solution, HAuCl
4Concentration be 0.5-2w/v%) in, ultrasonic dispersion number minute dilutes scattered solution with redistilled water.The dilute solution of handling well is placed micro-wave oven central authorities heat a few minutes (preferably 1-3 minute), acylate (described acylate is selected from sodium citrate, sodium molybdate) with appropriate amount joins in the hot solution again, microwave radiation number minute (preferably 4-6 minute).After cooling that the suspending liquid that obtains is centrifugal, filtration obtain the Au-NPs//CNTs nano composite material.
Au-NPs//CNTs nano composite material provided by the invention can be a liquid, also can be solid, and described solid product can be product liquid to be placed on dried overnight obtains in the vacuum drying oven.
Au-NPs/CNTs compound substance provided by the invention can be used for detecting the content of heavy metal Hg in the testing sample, in particular for the qualitative and/or quantitative measurement of trace Hg in the testing sample.
Au-NPs/CNTs compound substance provided by the invention to be used for detecting the content of testing sample heavy metal Hg, at first to obtain a kind of modified electrode, described modified electrode is decorating liquid is coated on the base electrode (described base electrode is selected from glass-carbon electrode, carbon class electrode) and obtains, described decorating liquid is that Au-NPs/CNTs compound substance provided by the invention is scattered in the organic solvent (described organic solvent is selected from dimethyl sulfoxide, Nafion solution), ultrasonicly evenly obtains.
Qualitative and/or the method for quantitatively determining of trace Hg (II) comprises step in a kind of testing sample provided by the invention:
(i) testing sample is joined in the electrolytic cell, with aforesaid modified electrode provided by the invention is working electrode, Ag/AgCl is a contrast electrode, the Pt silk is that auxiliary electrode constitutes three-electrode system, regulate sedimentation potential E=-0.2-0V, sedimentation time 60-300 second, thus trace Hg (II) is enriched on the aforesaid modified electrode provided by the invention;
(ii) regulate the stripping current potential between 0-0.8V, thereby make the heavy metal ion stripping; With
(iii) analyze trace Hg (II) ion stripping spike potential and electric current, obtain the qualitative and/or quantitative result of Hg in the testing sample (II).
The above-mentioned feature that the present invention mentions, or the feature that embodiment mentions can combination in any.All features that this case instructions is disclosed can with any composition forms and usefulness, each feature that is disclosed in the instructions can anyly provide the alternative characteristics of identical, impartial or similar purpose to replace.Therefore removing has special instruction, and the feature that is disclosed only is the general example of equalization or similar features.
Major advantage of the present invention is:
(1) electrode advantage of the present invention is that the preparation method is simple fast, microwave heating has significantly been shortened the reaction time, and synthetic need of traditional chemical surpasses one hour, and microwave radiation only need be less than ten minutes and gets final product.
(2) combination electrode golden nanometer particle of the present invention is littler, more even, and electrode specific surface area increases, and electrocatalysis characteristic improves, and the life-span of electrode prolongs.
(3) the detection response time of described electrode pair Hg is fast, the range of linearity is wide, highly sensitive, good stability, reusable, avoid electrode mechanical grinding etc.
(4) electrode preparation method of the present invention is simple and detection method is simple to operation, uses the instrument low price, and is with low cost, and is " environment-friendly type " electrode material, and repeated use can not cause environmental pollution, meets people for environmental protection requirement.
Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiment only to be used to the present invention is described and be not used in and limit the scope of the invention.The experimental technique of unreceipted actual conditions in the following example, usually according to people such as normal condition such as Sambrook, molecular cloning: lab guide (New York:Cold Spring Harbor Laboratory Press, 1989) condition described in, or the condition of advising according to manufacturer.Unless otherwise indicated, otherwise number percent and umber calculate by weight.
Unless otherwise defined, the same meaning that employed all specialties and scientific words and one skilled in the art are familiar with in the literary composition.In addition, any method similar or impartial to described content and material all can be applicable among the present invention.The usefulness that preferable implementation method described in the literary composition and material only present a demonstration.
Employed material in the embodiment of the invention:
Reagent
It is pure that all chemicals are analysis.HAuCl
46H
2O (99.9%), HClO
4, H
2SO
4, sodium citrate purchases the chemical company in U.S. Sigma-Aldrich; The Hg of 1000mg/L (II) standard solution is purchased the company in German Merck; Multi-walled carbon nano-tubes (diameter 20-30nm) is available from China Shenzhen Nanosolutions GmbH, and before the experiment, CNTs was with red fuming nitric acid (RFNA) backflow purifying four hours.
Instrument
CHI660a electrochemical analyser (Shanghai occasion China instrument company); Working electrode (SGE, Au-NPs/CNTs/GCE); Contrast electrode (Ag/AgCl); To electrode (Pt silk); (SGE, electrode area are 0.07cm to the gold disc electrode
2); Glass-carbon electrode (GCE, carbon class electrode); Micro-wave oven (microwave apparatus company limited is newly opened up in Shanghai); Transmission electron microscope (JEOL JEM 2010, Japan); Energy dispersive X-ray spectrum (S-4800, Hitachi, Japan).
Embodiment 1
Microwave radiation is synthesized Au-NPs/CNTs nano composite material 1
The CNTs of 1mg process pre-treatment is joined 1%HAuCl
4In the solution, ultrasonic dispersion 5 minutes is diluted to 100ml to scattered solution with redistilled water.The 100ml solution of handling well is placed the heating 60s of micro-wave oven central authorities, again 4ml sodium citrate (1%) is joined in the hot solution microwave radiation 2-5 minute.After cooling that the suspending liquid that obtains is centrifugal, filtration, solid product is placed on dried overnight in 120 ℃ of vacuum drying ovens, promptly obtains Au-NPs/CNTs nano composite material 1.
The pattern of Au-NPs/CNTs nano composite material and performance characterization
Figure 1A is the transmission electron microscope figure of the synthetic Au-NPs/CNTs compound substance of microwave radiation.As can be seen from the figure Au nano particle uniform load is on the CNTs surface, and these particles are relative uniform spherical, and mean diameter is 10 ± 3nm, does not have block or membranaceous gold and forms.The performance of microwave Fast Heating and strong penetrating power makes it accelerate reduction of metal ion and nucleation, has caused product to have little size and uniform dispersion degree.In addition, microwave heating has significantly been shortened the reaction time, and synthetic need of traditional chemical surpasses 1 hour, and a microwave radiation demand 4-6 minute.Energy dispersive X-ray spectrum figure (Figure 1B) has confirmed the formation of Au-NPs/CNTs compound substance equally.
Fig. 2 is the ultraviolet-visible absorption spectroscopy figure of nanometer gold size (a) and the synthetic Au-NPs/CNTs suspending liquid (b) after centrifugal.525nm is the absorption peak of golden nanometer particle, by drawing among the figure, 98% golden nanometer particle has loaded on the carbon nano-tube, have only a little golden nanometer particle to exist in solution, this shows, nearly all golden nanometer particle all loads on the carbon nano-tube, proves that the microwave radiation synthetic method has very high efficient.
Microwave radiation is synthesized Au-NPs/CNTs nano composite material 2
0.5mg is joined in the 0.5%HAuCl4 solution through the CNTs of pre-treatment, and ultrasonic dispersion 10 minutes is diluted to 100ml to scattered solution with redistilled water.The 100ml solution of handling well is placed the heating 120s of micro-wave oven central authorities, again 4ml sodium citrate (0.5%) is joined in the hot solution microwave radiation 2-5 minute.After cooling that the suspending liquid that obtains is centrifugal, filtration, solid product is placed on dried overnight in 120 ℃ of vacuum drying ovens, promptly obtains Au-NPs//CNTs nano composite material 2.
Embodiment 3
Microwave radiation is synthesized Au-NPs/CNTs nano composite material 3
2mg is joined in the 2%HAuCl4 solution through the CNTs of pre-treatment, and ultrasonic dispersion 15 minutes is diluted to 100ml to scattered solution with redistilled water.The 100ml solution of handling well is placed the heating 180s of micro-wave oven central authorities, again 4ml sodium citrate (2%) is joined in the hot solution microwave radiation 4-6 minute.After cooling that the suspending liquid that obtains is centrifugal, filtration, solid product is placed on dried overnight in 120 ℃ of vacuum drying ovens, promptly obtains Au-NPs//CNTs nano composite material 3.
The preparation modified electrode
At first, glass-carbon electrode after polishing on the W7 abrasive paper for metallograph, is used Al
2O
3(0.05 μ m) suspension sanding and polishing on chamois leather becomes minute surface, and successively at 1: 1 HNO
3With ultrasonic 5min in the water, natural airing is stand-by.
Then, among the DMF of the Au-NPs/CNTs nano composite material 1 ultrasonic 1ml of being scattered in that 0.5mg embodiment 1 is prepared, promptly obtain the suspending liquid of 0.5mg/ml.10 μ l hanging drops are to the glass-carbon electrode surface of handling well, and it is stand-by to treat to obtain Au-NPs/CNTs/GCE after the solvent DMF evaporation drying.
The chemical property of Au-NPs/CNTs compound substance
In order to characterize the chemical property of Au-NPs/CNTs compound substance better, adopt cyclic voltammetry to investigate this modified electrode at 0.1mol/L H
2SO
4Electrochemical properties in the solution.As shown in Figure 3, dotted line shows the electrochemical response at pure CNTs modified glassy carbon electrode, and all the non-oxidation reduction peak occurs.And curve (a) (b), then is that the different Au-NPs/CNTs that measure are modified on the naked glass-carbon electrode (c), is respectively the voltammogram of the suspending liquid of 5,10 and 15 μ l.
The result shows, the reduction peak of gold surface single layer oxide is arranged about+0.85V, and the electric weight that is consumed when reducing according to gold surface single layer oxide film is 400 μ C/cm
2, through calculating, the Au-NPs/CNTs/GCEs electroactive area is respectively 0.47,0.83and 0.92cm
2, this is than the area (0.07cm of naked glass-carbon electrode itself
2) improve 13 times nearly, also demonstrated higher electrochemical activity of Au-NPs/CNTs/GCEs and bigger specific surface area simultaneously.
Use 0.1mol/L H respectively
2SO
4, H
3PO
4, HCl, HClO
4And HNO
3Repeat above-mentioned experiment as electrolyte, Fig. 4 A is different acid solution 0.1mol/L H
2SO
4, H
3PO
4, HCl, HClO
4And HNO
3The synoptic diagram that influences to Hg (II) stripping peak current.
Fig. 4 B is the influence of deposition voltage to Hg (II) stripping electric current.As can be seen from the figure, deposition voltage is in-0.2-0.0V scope, and electric current increases with the rising of voltage; But along with the direction of voltage to corrigendum moves, electric current descends on the contrary thereupon.
Embodiment 5
The electrochemical response performance of solid gold disc electrode and Au-NPs/CNTs combination electrode relatively
In order to investigate the electrochemical response performance of Au-NPs/CNTs composite electrode to mercury, present embodiment adopts differentiated pulse cyclic voltammetry (DPASV) to detect.
Trace Hg solution is joined in the electrolytic cell, preparing Au-NPs/CNTs modified electrode and solid gold disc electrode with embodiment 2 respectively is working electrode, Ag/AgCl is a contrast electrode, the Pt silk is that auxiliary electrode constitutes three-electrode system, regulate sedimentation potential E=-0.1V, sedimentation time 120 seconds, thus trace Hg (II) is enriched on the working electrode;
(b) after deposition finishes, static 10 seconds of solution;
(c) regulate the stripping current potential between 0-0.8V, thereby make heavy metal ion oxidation stripping again;
(d) analyze trace Hg (II) ion stripping spike potential and electric current.Determine the character of mercury according to spike potential, calculate the content of mercury according to the size of peak current.
The results are shown in Figure 5.From Fig. 5 (a) as can be seen, upward occur at the CNTs/GCE of no Au-NPs load (solid gold disc electrode) without any Hg (II) stripping peak.Yet Au-NPs/CNTs/GCE has but shown the electrochemical response good to mercury (Fig. 5 (c)) ,+tangible mercury stripping oxidation peak appears in the 0.63V place.
The result shows that the Au-NPs/CNTs compound substance has good electrochemical response to Hg (II).Compare (Fig. 5 (b)) with SGE, Au-NPs/CNTs/GCE has greatly increased Hg stripping peak current (nearly 60%), this may be since load on Au nano particle diameter on the CNTs less, be evenly distributed, have bigger electroactive area, and then Hg (II) voltammetric current enlarges markedly.
Solid gold disc electrode and Au-NPs/CNTs combination electrode are applied to the comparison of Hg (II) standard curve determination
The Au-NPs/CNTs combination electrode of using solid gold disc electrode (SGE) and embodiment 2 to prepare respectively is applied to Hg (II) standard curve determination.
The Hg standard solution is joined in the electrolytic cell, preparing Au-NPs/CNTs modified electrode and solid gold disc electrode with embodiment 2 respectively is working electrode, Ag/AgCl is a contrast electrode, the Pt silk is that auxiliary electrode constitutes three-electrode system, regulate sedimentation potential E=-0.1V, sedimentation time 120 seconds, thus trace Hg (II) is enriched on the working electrode;
(b) after deposition finishes, static 10 seconds of solution;
(c) regulate the stripping current potential between 0-0.8V, thereby make heavy metal ion oxidation stripping again;
(d) analyze trace Hg (II) ion stripping spike potential and electric current, the quantity of the Hg that adds according to standard obtains typical curve, calculates the content of Hg.
During with solid gold disc electrode (SGE), Hg (II) range of linearity is respectively 3 * 10
-9-2.5 * 10
-8Mol/L (Fig. 6 A) and 3 * 10
-8-6 * 10
-7Mol/L (Fig. 6 B).Under low consistency conditions, the peak current of mercury and concentration present favorable linearity and increase progressively relation, and its related coefficient is 0.995 (Fig. 6 A).In concentration range is 3 * 10
-8-5 * 10
-7During mol/L, still keep good linear relationship with peak current.But mercury concentration surpasses 5 * 10
-7During mol/L, the stripping peak current no longer significantly increases, and Hg (II) concentration and electric current be departs from linear (Fig. 6 B) slowly.This is because along with mercury concentration increases, the mercury amount that is enriched in electrode surface increases, mercury easily is diffused into the solid gold electrode surfaces, be difficult for stripping and cleaning, the electrode surface residual mercury that is easy to get, cause testing result reappearance and stability to reduce greatly, the biggest problem that this runs into when being solid gold disc electrode detection mercury.Under two minutes the enrichment time, the detectability of this method (S/N=3) as calculated is derived as 1 * 10
-9Mol/L.
During with Au-NPs/CNTs nano composite material electrode, the range of linearity of Hg (II) is respectively 5 * 10
-10-5 * 10
-9Mol/L (Fig. 7 A), 5 * 10
-8-1.25 * 10
-6Mol/L (Fig. 7 B).From Fig. 7 A and 7B as can be seen, no matter be low concentration or high concentration, this composite electrode all has fabulous electrochemical response to Hg (II), and the stripping peak current becomes good linear relationship with mercury concentration, and its related coefficient is respectively 0.9975 and 0.998 (Fig. 8).
The result shows, identical phenomenon all occurred on SGE and Au-NPs/CNTs nano composite material electrode, and promptly mercury concentration is low more, and sensitivity is high more.The enrichment time of 2min, Au-NPs/CNTs nano composite material electrode pair Hg (II) detects and is limited to 3 * 10
-10Mol/L (0.06 μ g/L).When if enrichment time is 5min, the detectability of mercury can be low to moderate 1 * 10
-10Mol/L (0.02 μ g/L).
Obviously, compare with SGE, the Au-NPs/CNTs combination electrode has represented the wideer range of linearity and lower detectability, the synthetic golden nanometer particle of microwave radiation loads on the CNTs, has bigger useful area owing to its particle diameter is little, electrode surface is difficult for reaching capacity when being applied to the detection of Hg (II), thereby has enlarged its range of linearity; Simultaneously, because the small-size effect of golden nanometer particle, the catalytic performance of this combination electrode also greatly improves, and has reduced the detectability of method.In addition, utilize the synthetic golden nanometer particle of microwave radiation firmly to load on the carbon nano tube surface, can not come off in experiment easily, therefore, this electrode reappearance and stability also increase greatly.
Embodiment 7
The mensuration of actual sample
Surface water 5ml to be measured is joined in the electrolytic cell, the Au-NPs/CNTs modified electrode for preparing with embodiment 2 is a working electrode, Ag/AgCl is a contrast electrode, the Pt silk is that auxiliary electrode constitutes three-electrode system, regulate sedimentation potential E=-0.1V, sedimentation time 120 seconds, thus trace Hg (II) is enriched on the electrode of the present invention;
(b) after deposition finishes, static 10 seconds of solution;
(c) regulate the stripping current potential between 0-0.8V, thereby make heavy metal ion oxidation stripping again;
(d) analyze trace Hg (II) ion stripping spike potential and electric current, thereby learn the content of Hg in the testing sample according to standard addition method.
Fig. 8 is applied to detect the stripping voltammogram of face of land underwater trace Hg (II) for Au-NPs/CNTs nano composite material electrode.As can be seen from Figure, the Au-NPs/CNTs combination electrode has electrochemical signals in surface water solution, the stripping peak appears at+0.63V, add the Hg standard solution, this stripping peak current increases, and proves that this peak is the oxidation stripping peak of Hg, make this combination electrode detect face of land underwater trace Hg (II) and become possibility, according to standard addition method, as calculated, the content of Hg is (1.2 ± 0.2) * 10 in this surface water
-8Mol/L (n=4).
The microwave radiation for preparing with embodiment 2 and embodiment 3 is synthesized Au-NPs/CNTs nano composite material 2 and 3 respectively, method by embodiment 4 obtains corresponding modified electrode Au-NPs/CNTs/GCE, the modified electrode that obtains is measured the actual sample among the embodiment 7, can be obtained the content of Hg in the surface water equally.
Discuss
The Au-NPs/CNTs biggest advantage is can be applied to produce electrochemical sensor in enormous quantities, to keep the regeneration of electrode surface.When SGE measures Hg (II), mercury has stronger suction-operated to the gold dish, even after adopting the electrochemical method cleaning electrode, some Hg (II) still remain in electrode surface, the performance of electrode is because the suction-operated of mercury is destroyed like this, still can not obtain a no mercury, clean golden panel surface after galvanochemistry is cleaned, influence the reappearance and the accuracy of electrode greatly.
As a rule, the solid gold electrode can only be used the alumina powder mechanical grinding, but can damage its surperficial smooth degree gradually like this, influences its performance and application.And utilize electrochemical deposition, the method that Jenner's particle the is deposited on electrode surface part that also comes with some shortcomings at first, can only be modified unitary electrode at every turn.Secondly, after experiment finished, the process of removing the golden nanometer particle layer on the electrode surface was not only consuming time and complicated, has so just limited this method and has been applied to detect large batch of sample.
Utilize the synthetic Au-NPs/CNTs homogeneous of microwave radiation, stable, and, be coated onto on the electrode as long as complex dripped, be easy to obtain a new modified electrode, therefore can produce reproducible sensor in enormous quantities, as detecting a large amount of samples.
Utilize the synthetic Au-NPs/CNTs of microwave radiation to also have a unique advantage simultaneously, promptly this method also can significantly reduce the consumption of gold solution.Adopt the Au-NPs/CNTs composite electrode to repeat above-mentioned experiment for several times in 10 months, relative standard deviation is all in 5%.Therefore, this composite electrode detection Trace Hg has great application prospect.
The invention provides the fast synthetic Au-NPs/CNTs nano composite material of microwave radiation, and with it as working electrode, confirmed that the stripping of Au-NPs/CNTs/GCE anode detects the feasibility of Trace Hg (II).The major advantage of this new method is: (1) microwave heating has significantly been shortened the reaction time, and synthetic need of traditional chemical surpasses one hour, and microwave radiation only need be less than ten minutes and gets final product.And the Au-NPs homogeneous is dispersed in the CNTs surface, than have littler particle (10 ± 3nm) with electrochemical deposition method; (2) with the solid gold electrode relatively, Au-NPs/CNTs/GCE has greatly improved the electrochemical response performance, has represented that the range of linearity is fast, highly sensitive, high repeatability and other advantages; (3) this method can be used to produce in enormous quantities reproducible sensor, can avoid removing the consuming time and complicated process of golden nanometer particle layer on the electrode surface.Nano composite material electrode of the present invention provides new method and thinking for Trace Hg in the testing environment and mercury salt aspect.
The above only is preferred embodiment of the present invention, be not in order to limit essence technology contents scope of the present invention, essence technology contents of the present invention is broadly to be defined in the claim scope of application, any technology entity or method that other people finish, if it is defined identical with the claim scope of application, also or a kind of change of equivalence, all will be regarded as being covered by among this claim scope.
Claims (10)
1. the preparation method of a golden nanometer particle/carbon nano tube compound material (Au-NPs/CNTs compound substance) is characterized in that described method comprises step:
(1) with carbon nano-tube and HAuCl
4Solution mixes, and microwave heating 1-3 minute, obtains hot solution 1;
(2) hot solution 1 and sodium citrate solution are mixed, microwave radiation 4-6 minute, obtain hot solution 2; With
(3) hot solution 2 is cooled to room temperature, obtains suspending liquid, centrifugal, filtration obtains golden nanometer particle/carbon nano tube compound material.
2. preparation method as claimed in claim 1 is characterized in that, with HAuCl
4The cumulative volume meter of solution, HAuCl
4Concentration be 0.5-2w/v%.
3. preparation method as claimed in claim 1 is characterized in that, in the step (2), the blending ratio of carbon nano-tube and sodium citrate is 0.5-2mg: 4ml; In the cumulative volume of sodium citrate solution, the concentration of sodium citrate is 0.5-2w/v%.
4. golden nanometer particle/carbon nano tube compound material that obtains as the arbitrary described preparation method of claim 1-3.
5. the purposes of a golden nanometer particle/carbon nano tube compound material as claimed in claim 4 is characterized in that, is used for detecting the content of testing sample heavy metal Hg.
6. purposes as claimed in claim 5 is characterized in that, is used for the qualitative and/or quantitative measurement of testing sample trace Hg.
7. a modified electrode is characterized in that, described modified electrode comprises:
One base electrode, i.e. glass-carbon electrode;
One is coated on the golden nanometer particle/carbon nano tube compound material as claimed in claim 4 on base electrode surface.
8. modified electrode as claimed in claim 7 is characterized in that, the amount of golden nanometer particle/carbon nano tube compound material is 5-15 μ l.
9. the preparation method of a modified electrode as claimed in claim 7 is characterized in that, described method comprises step:
(a) golden nanometer particle/carbon nano tube compound material as claimed in claim 4 and dimethyl sulfoxide (DMF) are mixed, obtain decorating liquid; With
(b) will modify drop and be applied to the glass-carbon electrode surface, obtain modified electrode as claimed in claim 8.
10. the qualitative and/or method for quantitatively determining of trace Hg (II) in the testing sample is characterized in that described method comprises step:
(i) testing sample is joined in the electrolytic cell, with modified electrode as claimed in claim 7 is working electrode, Ag/AgCl is a contrast electrode, the Pt silk is that auxiliary electrode constitutes three-electrode system, regulate sedimentation potential E=-0.2-0V, sedimentation time 60-300 second, thus trace Hg (II) is enriched on the modified electrode as claimed in claim 8;
(ii) regulate the stripping current potential between 0-0.8V, thereby make the heavy metal ion stripping; With
(iii) analyze trace Hg (II) ion stripping spike potential and electric current, obtain the qualitative and/or quantitative result of Hg in the testing sample (II).
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